There are two fundamental technical goals which must be reached before hyperthermia can become a practical and efficacious adjuvant treatment modality. The first is the development of equipment which can adequately heat tumors. The second (which is the goal of this research) is the development of methods for accurately simulating and estimating the complete temperature distributions in heated tumors. Without such simulation abilities it is not possible: l) to accurately plan patient treatments; 2) to properly control the power deposition patterns of the complex, flexible heating modalities which are needed for adequately heating tumors; or, 3) to retrospectively determine the thermal efficacy of any given treatment--since current clinical practice only samples temperatures at a small number of points. Clearly, these are three fundamental, indispensable needs for the successful development of hyperthermia, and until such simulation tools are available hyperthermia has little chance of becoming a successful, practical and clinically useful treatment modality. (By comparison, one would not imagine performing a radiation treatment without some preliminary simulations of the expected doses.) The following steps will be taken to develop those tools. l. Continued development of improved, more fundamental methods for modeling and simulating the distributions of temperatures in heated tissues. It is clear from the work of ourselves and others that a more fundamental approach to modeling tissues is needed to replace (or at the very least augment) the currently used Pennes' bio-heat transfer equation and effective conductivity equation approximations. This will be done by further development of our thermal models that characterize tissues as consisting of an underlying solid tissue matrix that is interspersed with a network of blood vessels and is governed by the fundamental convective energy equation. Specific tasks to be performed are: development of improved mathematical representations of these new tissue thermal models; acquisition of more complete data on the 3D distributions and sizes of blood vessels in in vivo, spontaneous human tumors and their adjacent normal tissues, and of the flow rates in those vessels; development of algorithms for quantifying those characteristics for the thermally relevant vessels; incorporation of those quantified distributions and velocities in the new thermal models; and, theoretical, experimental and clinical evaluations of those models. 2. Development of improved state and parameter estimation techniques using these new, more fundamentally based thermal tissue models. These estimation techniques will be used for both retrospective evaluations of treatments and for on line feedback control applications. 3. Development and distribution of a practical, clinically useful 3D patient treatment planning program that is based on patient specific heterogeneous tissue descriptions, and on large blood vessel data when that information is clinically available. This resource will be applicable to the treatment of all solid tumors, including brain, breast, prostate, superficial, and deep seated abdominal and pelvic tumors.